I have done some work on automotive power electronics. Cant say much, but if you are serious, look into power conversion. You will achieve much higher efficiency at higher voltages. Most automotive power engineers agree high power systems cannot be run on less than a 42v core. FYI the next gen Toyota hybrid will be running a 42v battery to a sealed voltage converter to a 300-500v core ISA.
Now I would love to see it when its done, but every application of e-turbos I've seen is supplimental. Turbos alone are very very efficent, however they tend to have lag. E-turbos have no lag, but use lots of power. Once combined the system works very well, the e gets the engine to speed and starts the turbo, which then takes over. Some systems are even so advanced that the e-turbo can extract power and prevent over-boost without a bov.
